mdns.c: use group initializer constants from prot/dns.h
diff --git a/src/apps/mdns/mdns.c b/src/apps/mdns/mdns.c
index e90c544..631e2ce 100644
--- a/src/apps/mdns/mdns.c
+++ b/src/apps/mdns/mdns.c
@@ -81,13 +81,13 @@
 #if LWIP_IPV4
 #include "lwip/igmp.h"
 /* IPv4 multicast group 224.0.0.251 */
-static const ip_addr_t v4group = IPADDR4_INIT(PP_HTONL(0xE00000FBUL));
+static const ip_addr_t v4group = DNS_MQUERY_IPV4_GROUP_INIT;
 #endif
 
 #if LWIP_IPV6
 #include "lwip/mld6.h"
 /* IPv6 multicast group FF02::FB */
-static const ip_addr_t v6group = IPADDR6_INIT(PP_HTONL(0xFF020000UL), PP_HTONL(0x00000000UL), PP_HTONL(0x00000000UL), PP_HTONL(0x000000FBUL));
+static const ip_addr_t v6group = DNS_MQUERY_IPV6_GROUP_INIT;
 #endif
 
 #define MDNS_PORT 5353